Building Li-ION Battery Packs

**xwingband** · 12-28-2006, 08:50 AM

I don't know where you're seeing 2000mah ones, but I expect them to be similar to this in amperage:
http://www.batteryspace.com/index.as...OD&ProdID=2426

My problem is that there isn't a good charger for them that I've seen. They're benifits are marginal too when paralleled. You can get a 18650 that is roughly the same size that gets 2600mah compared to 2 CR123's at around 1400mah.

It's nice that they can be 3V, but otherwise I haven't figured yet how to make them useful in a rechargeable situation with out having something better.

**LordArgyll** · 12-28-2006, 09:10 AM

I was reading an independent review on the Delkin RCR123A over on the CandlePowerForums.

http://www.candlepowerforums.com/vb/...ad.php?t=73460

The battery is supposedly rated at 2000mA but the guy got a reading of 6000mA off of it in a burst.

Unfortunately I can't seem to find the "official" factory specs, but if it's true, they might be useful.

Regarding the 18650s... if one were to build a pack with them (or any Li-Ion for that matter) would you recommend a protection circuit? Or should a "smart" charger be sufficient to minimize the exploding hazard?

**xwingband** · 12-28-2006, 09:45 AM

What they guy is talking about there is 2A of output. That doesn't mean that's the capacity... just that it can put out that much at a time.

So if a 1A battery is outputting 2A then it'll be deader than a door nail in 30 minutes.

As for protection circuits... I've never done them. They are not as much for the exploding as they are to condition the battery well and not expell all of it's power (bad for li-ions).

However since Luxeons will not light after a certain point of voltage I've never had a problem without the PCB protection.

If that review is true and they're putting out that much voltage I wouldn't even bother with them. So far 3V was the only benefit I saw.

**LordArgyll** · 12-28-2006, 09:53 AM

Guess I'll go with the 2600mAh 18650s then. Thanks for your input!

**LordArgyll** · 01-12-2007, 07:20 AM

Wow... so the 18650s are huge. I could see them being useful in a sink tube saber, but as far as an MHS saber is concerned, unless you plan on having a grossly oversized hilt or a direct drive setup, they seem like something to avoid. My saber is a ribbed section with two 2.5" extensions and there's just no room to fix 2x18650s plus driver board and sound and switch wiring.

Well... chalk it up to a lesson learned... measure before you buy.

**Strydur** · 01-12-2007, 09:30 AM

Yes they are. You could use just one for a 3w or k2 though. You can also get them setup end to end and they would work for a 5w.

**xwingband** · 01-12-2007, 03:21 PM

Yeah, end to end in a ribbed section would work well.

**Jedi Ranger** · 02-17-2007, 12:08 AM

Does anyone know where I might find a stick-form battery holder for 2 of the 18650 cells? I'd like to build a couple packs (either with or without the protection board).

Or...........can anyone give some pointers on building custom 7.2v li-ion packs from (2) 18650 cells. Removable batteries would be best, so I can recharge them faster.

**Madcow** · 02-17-2007, 11:18 AM

I figured that might be a problem.
Juging by your craftsmanship Arg - you'll figure something out.

I had a friend build me packs out of 8 AAA NIMH cells each. (4 cells in series - paralelled to another 4 in series). The end result is a 4.8 volt pack that puts out 2000 mAh, and fits inside 1" ID.
I just measured the voltage on one pack fully charged and it was 5.4 volts! I was expecting no more than 5v. I wonder if my charger is overcharging the pack - or if this is normal...

Any thoughts?

BTW - how do smart chargers detect when the pack is charged?
Mycharger is this one...
http://www.hobbico.com/chargers/hcap0290.html

MC